/*
 * This file is part of the Berlioz library.
 *
 * For licensing information please see the file license.txt included in the release.
 * A copy of this licence can also be found at
 *   http://www.opensource.org/licenses/artistic-license-2.0.php
 */
package org.weborganic.berlioz.util;

import java.io.File;
import java.io.IOException;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;

/**
 * <p>Encodes and decodes to and from Base64 notation.</p>
 *
 *
 * <p>Example:</p>
 *
 * <code>String encoded = Base64.encode( myByteArray );</code>
 * <br />
 * <code>byte[] myByteArray = Base64.decode( encoded );</code>
 *
 * <p>The <tt>options</tt> parameter, which appears in a few places, is used to pass
 * several pieces of information to the encoder. In the "higher level" methods such as
 * encodeBytes( bytes, options ) the options parameter can be used to indicate such
 * things as first gzipping the bytes before encoding them, not inserting linefeeds,
 * and encoding using the URL-safe and Ordered dialects.</p>
 *
 * <p>Note, according to <a href="http://www.faqs.org/rfcs/rfc3548.html">RFC3548</a>,
 * Section 2.1, implementations should not add line feeds unless explicitly told
 * to do so. I've got Base64 set to this behavior now, although earlier versions
 * broke lines by default.</p>
 *
 * <p>The constants defined in Base64 can be OR-ed together to combine options, so you
 * might make a call like this:</p>
 *
 * <code>String encoded = Base64.encodeBytes( mybytes, Base64.GZIP | Base64.DO_BREAK_LINES );</code>
 * <p>to compress the data before encoding it and then making the output have newline characters.</p>
 * <p>Also...</p>
 * <code>String encoded = Base64.encodeBytes( crazyString.getBytes() );</code>
 *
 *
 * <p>The code of this class is essentially based on version 2.3.7 of the Base64 class developed
 * by Robert Harder and is in the Public Domain.
 *
 * @see <a href="http://iharder.net/base64">http://iharder.net/base64</a>.</p>
 *
 * @author Robert Harder
 * @author rob@iharder.net
 * @author Christophe Lauret
 *
 * @version Berlioz 0.9.32
 * @since Berlioz 0.9.32
 */
public final class Base64 {

  // Public fields
  // ----------------------------------------------------------------------------------------------

  /** No options specified. Value is zero. */
  public static final int NO_OPTIONS = 0;

  /** Specify encoding in first bit. Value is one. */
  public static final int ENCODE = 1;

  /** Specify decoding in first bit. Value is zero. */
  public static final int DECODE = 0;

  /** Specify that data should be gzip-compressed in second bit. Value is two. */
  public static final int GZIP = 2;

  /** Specify that gzipped data should <em>not</em> be automatically gunzipped. */
  public static final int DONT_GUNZIP = 4;

  /** Do break lines when encoding. Value is 8. */
  public static final int DO_BREAK_LINES = 8;

  /**
   * Encode using Base64-like encoding that is URL- and Filename-safe as described
   * in Section 4 of RFC3548:
   * <a href="http://www.faqs.org/rfcs/rfc3548.html">http://www.faqs.org/rfcs/rfc3548.html</a>.
   * It is important to note that data encoded this way is <em>not</em> officially valid Base64,
   * or at the very least should not be called Base64 without also specifying that is
   * was encoded using the URL- and Filename-safe dialect.
   */
  public static final int URL_SAFE = 16;

  /**
   * Encode using the special "ordered" dialect of Base64 described here:
   * <a href="http://www.faqs.org/qa/rfcc-1940.html">http://www.faqs.org/qa/rfcc-1940.html</a>.
   */
  public static final int ORDERED = 32;

  // Private fields
  // ----------------------------------------------------------------------------------------------

  /** Maximum line length (76) of Base64 output. */
  private static final int MAX_LINE_LENGTH = 76;

  /** The equals sign (=) as a byte. */
  private static final byte EQUALS_SIGN = (byte)'=';

  /** The new line character (\n) as a byte. */
  private static final byte NEW_LINE = (byte)'\n';

  /** Preferred encoding. */
  private static final String PREFERRED_ENCODING = "US-ASCII";

  /** Indicates white space in encoding. */
  private static final byte WHITE_SPACE_ENC = -5;

  /** Indicates equals sign in encoding. */
  private static final byte EQUALS_SIGN_ENC = -1;

  // STANDARD  BASE64  ALPHABET
  // ----------------------------------------------------------------------------------------------

  /**
   * The 64 valid Base64 values.
   * (Host platform me be something funny like EBCDIC, so we hardcode these values.)
   */
  private static final byte[] STANDARD_ALPHABET = {
      (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
      (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
      (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
      (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
      (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
      (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
      (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
      (byte)'v', (byte)'w', (byte)'x', (byte)'y', (byte)'z',
      (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5',
      (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'+', (byte)'/'
  };

  /**
   * Translates a Base64 value to either its 6-bit reconstruction value
   * or a negative number indicating some other meaning.
   **/
  private static final byte[] STANDARD_DECODABET = {
      -9, -9, -9, -9, -9, -9, -9, -9, -9,                 // Decimal  0 -  8
      -5, -5,                                             // Whitespace: Tab and Linefeed
      -9, -9,                                             // Decimal 11 - 12
      -5,                                                 // Whitespace: Carriage Return
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
      -9, -9, -9, -9, -9,                                 // Decimal 27 - 31
      -5,                                                 // Whitespace: Space
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,             // Decimal 33 - 42
      62,                                                 // Plus sign at decimal 43
      -9, -9, -9,                                         // Decimal 44 - 46
      63,                                                 // Slash at decimal 47
      52, 53, 54, 55, 56, 57, 58, 59, 60, 61,             // Numbers zero through nine
      -9, -9, -9,                                         // Decimal 58 - 60
      -1,                                                 // Equals sign at decimal 61
      -9, -9, -9,                                         // Decimal 62 - 64
      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,       // Letters 'A' through 'N'
      14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,     // Letters 'O' through 'Z'
      -9, -9, -9, -9, -9, -9,                             // Decimal 91 - 96
      26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
      39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
      -9, -9, -9, -9, -9,                                 // Decimal 123 - 127
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,     // Decimal 128 - 139
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 140 - 152
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 153 - 165
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 166 - 178
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 179 - 191
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 192 - 204
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 205 - 217
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 218 - 230
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 231 - 243
      -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9      // Decimal 244 - 255
  };

  // URL-Safe Base 64 alphabet
  // ----------------------------------------------------------------------------------------------

  /**
   * Used in the URL- and Filename-safe dialect described in Section 4 of RFC3548:
   * <a href="http://www.faqs.org/rfcs/rfc3548.html">http://www.faqs.org/rfcs/rfc3548.html</a>.
   *
   * Notice that the last two bytes become "hyphen" and "underscore" instead of "plus" and "slash."
   */
  private static final byte[] URL_SAFE_ALPHABET = {
    (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
    (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
    (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
    (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
    (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
    (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
    (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
    (byte)'v', (byte)'w', (byte)'x', (byte)'y', (byte)'z',
    (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5',
    (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'-', (byte)'_'
  };

  /**
   * Used in decoding URL- and Filename-safe dialects of Base64.
   */
  private static final byte[] URL_SAFE_DECODABET = {
    -9, -9, -9, -9, -9, -9, -9, -9, -9,                 // Decimal  0 -  8
    -5, -5,                                             // Whitespace: Tab and Linefeed
    -9, -9,                                             // Decimal 11 - 12
    -5,                                                 // Whitespace: Carriage Return
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
    -9, -9, -9, -9, -9,                                 // Decimal 27 - 31
    -5,                                                 // Whitespace: Space
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,             // Decimal 33 - 42
    -9,                                                 // Plus sign at decimal 43
    -9,                                                 // Decimal 44
    62,                                                 // Minus sign at decimal 45
    -9,                                                 // Decimal 46
    -9,                                                 // Slash at decimal 47
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61,             // Numbers zero through nine
    -9, -9, -9,                                         // Decimal 58 - 60
    -1,                                                 // Equals sign at decimal 61
    -9, -9, -9,                                         // Decimal 62 - 64
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,       // Letters 'A' through 'N'
    14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,     // Letters 'O' through 'Z'
    -9, -9, -9, -9,                                     // Decimal 91 - 94
    63,                                                 // Underscore at decimal 95
    -9,                                                 // Decimal 96
    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
    39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
    -9, -9, -9, -9, -9,                                 // Decimal 123 - 127
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,     // Decimal 128 - 139
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 140 - 152
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 153 - 165
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 166 - 178
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 179 - 191
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 192 - 204
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 205 - 217
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 218 - 230
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 231 - 243
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9      // Decimal 244 - 255
  };

  // Ordered Base64 Alphabet
  // ----------------------------------------------------------------------------------------------

  /**
   * I don't get the point of this technique,  but someone requested it,
   * and it is described here:
   * <a href="http://www.faqs.org/qa/rfcc-1940.html">http://www.faqs.org/qa/rfcc-1940.html</a>.
   */
  private static final byte[] ORDERED_ALPHABET = {
    (byte)'-',
    (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4',
    (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9',
    (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
    (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
    (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
    (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
    (byte)'_',
    (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
    (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
    (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
    (byte)'v', (byte)'w', (byte)'x', (byte)'y', (byte)'z'
  };

  /**
   * Used in decoding the "ordered" dialect of Base64.
   */
  private static final byte[] ORDERED_DECODABET = {
    -9, -9, -9, -9, -9, -9, -9, -9, -9,                 // Decimal  0 -  8
    -5, -5,                                             // Whitespace: Tab and Linefeed
    -9, -9,                                             // Decimal 11 - 12
    -5,                                                 // Whitespace: Carriage Return
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
    -9, -9, -9, -9, -9,                                 // Decimal 27 - 31
    -5,                                                 // Whitespace: Space
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9,             // Decimal 33 - 42
    -9,                                                 // Plus sign at decimal 43
    -9,                                                 // Decimal 44
    0,                                                  // Minus sign at decimal 45
    -9,                                                 // Decimal 46
    -9,                                                 // Slash at decimal 47
    1, 2, 3, 4, 5, 6, 7, 8, 9, 10,                      // Numbers zero through nine
    -9, -9, -9,                                         // Decimal 58 - 60
    -1,                                                 // Equals sign at decimal 61
    -9, -9, -9,                                         // Decimal 62 - 64
    11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, // Letters 'A' through 'M'
    24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, // Letters 'N' through 'Z'
    -9, -9, -9, -9,                                     // Decimal 91 - 94
    37,                                                 // Underscore at decimal 95
    -9,                                                 // Decimal 96
    38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, // Letters 'a' through 'm'
    51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, // Letters 'n' through 'z'
    -9, -9, -9, -9, -9,                                 // Decimal 123 - 127
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 128 - 139
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 140 - 152
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 153 - 165
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 166 - 178
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 179 - 191
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 192 - 204
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 205 - 217
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 218 - 230
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 231 - 243
    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9      // Decimal 244 - 255
  };

  // Determine which alphabet
  // ----------------------------------------------------------------------------------------------

  /**
   * Returns one of the byte arrays depending on the options specified.
   *
   * It's possible, though silly, to specify ORDERED <b>and</b> URLSAFE in which case one of
   * them will be picked, though there is no guarantee as to which one will be picked.
   *
   * @param options the options
   *
   * @return the corresponding alphabet
   */
  private static byte[] getAlphabet(int options) {
    if ((options & URL_SAFE) == URL_SAFE) return URL_SAFE_ALPHABET;
    else if ((options & ORDERED) == ORDERED) return ORDERED_ALPHABET;
    else return STANDARD_ALPHABET;
  }

  /**
   * Returns one of the "decodabet" byte array depending on the options specified.
   *
   * It's possible, though silly, to specify ORDERED and URL_SAFE in which case one of them will
   * be picked, though there is no guarantee as to which one will be picked.
   *
   * @param options the options
   *
   * @return the corresponding "decodabet"
   */
  private static byte[] getDecodabet(int options) {
    if ((options & URL_SAFE) == URL_SAFE) return URL_SAFE_DECODABET;
    else if ((options & ORDERED) == ORDERED) return ORDERED_DECODABET;
    else return STANDARD_DECODABET;
  }

  /**
   * Defeats instantiation.
   */
  private Base64() { }

  // Encoding Methods
  // ----------------------------------------------------------------------------------------------

  /**
   * Encodes up to the first three bytes of array <var>threeBytes</var>
   * and returns a four-byte array in Base64 notation.
   * The actual number of significant bytes in your array is
   * given by <var>numSigBytes</var>.
   * The array <var>threeBytes</var> needs only be as big as
   * <var>numSigBytes</var>.
   * Code can reuse a byte array by passing a four-byte array as <var>b4</var>.
   *
   * @param b4 A reusable byte array to reduce array instantiation
   * @param threeBytes the array to convert
   * @param numSigBytes the number of significant bytes in your array
   *
   * @return four byte array in Base64 notation.
   * @since 1.5.1
   */
  private static byte[] encode3to4(byte[] b4, byte[] threeBytes, int numSigBytes, int options) {
    encode3to4(threeBytes, 0, numSigBytes, b4, 0, options);
    return b4;
  }


  /**
   * <p>Encodes up to three bytes of the array <var>source</var>
   * and writes the resulting four Base64 bytes to <var>destination</var>.
   * The source and destination arrays can be manipulated
   * anywhere along their length by specifying
   * <var>srcOffset</var> and <var>destOffset</var>.
   * This method does not check to make sure your arrays
   * are large enough to accomodate <var>srcOffset</var> + 3 for
   * the <var>source</var> array or <var>destOffset</var> + 4 for
   * the <var>destination</var> array.
   * The actual number of significant bytes in your array is
   * given by <var>numSigBytes</var>.</p>
   * <p>This is the lowest level of the encoding methods with
   * all possible parameters.</p>
   *
   * @param source the array to convert
   * @param srcOffset the index where conversion begins
   * @param numSigBytes the number of significant bytes in your array
   * @param destination the array to hold the conversion
   * @param destOffset the index where output will be put
   * @return the <var>destination</var> array
   * @since 1.3
   */
  private static byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset, int options) {
    byte[] alphabet = getAlphabet(options);

    //           1         2         3
    // 01234567890123456789012345678901 Bit position
    // --------000000001111111122222222 Array position from threeBytes
    // --------|    ||    ||    ||    | Six bit groups to index ALPHABET
    //          >>18  >>12  >> 6  >> 0  Right shift necessary
    //                0x3f  0x3f  0x3f  Additional AND

    // Create buffer with zero-padding if there are only one or two significant bytes passed in the array.
    // We have to shift left 24 in order to flush out the 1's that appear
    // when Java treats a value as negative that is cast from a byte to an int.
    int inBuff =   (numSigBytes > 0 ? ((source[ srcOffset     ] << 24) >>>  8) : 0)
                 | (numSigBytes > 1 ? ((source[ srcOffset + 1 ] << 24) >>> 16) : 0)
                 | (numSigBytes > 2 ? ((source[ srcOffset + 2 ] << 24) >>> 24) : 0);

    switch(numSigBytes) {
      case 3:
        destination[ destOffset     ] = alphabet[ (inBuff >>> 18)        ];
        destination[ destOffset + 1 ] = alphabet[ (inBuff >>> 12) & 0x3f ];
        destination[ destOffset + 2 ] = alphabet[ (inBuff >>>  6) & 0x3f ];
        destination[ destOffset + 3 ] = alphabet[ (inBuff       ) & 0x3f ];
        return destination;

      case 2:
        destination[ destOffset     ] = alphabet[ (inBuff >>> 18)        ];
        destination[ destOffset + 1 ] = alphabet[ (inBuff >>> 12) & 0x3f ];
        destination[ destOffset + 2 ] = alphabet[ (inBuff >>>  6) & 0x3f ];
        destination[ destOffset + 3 ] = EQUALS_SIGN;
        return destination;

      case 1:
        destination[ destOffset     ] = alphabet[ (inBuff >>> 18)        ];
        destination[ destOffset + 1 ] = alphabet[ (inBuff >>> 12) & 0x3f ];
        destination[ destOffset + 2 ] = EQUALS_SIGN;
        destination[ destOffset + 3 ] = EQUALS_SIGN;
        return destination;

      default:
        return destination;
    }
  }

  /**
   * Performs Base64 encoding on the <code>raw</code> ByteBuffer, writing it to the
   * <code>encoded</code> ByteBuffer.
   *
   * This is an experimental feature. Currently it does not pass along any options
   * (such as {@link #DO_BREAK_LINES} or {@link #GZIP}.
   *
   * @param raw input buffer
   * @param encoded output buffer
   * @since 2.3
   */
  public static void encode(java.nio.ByteBuffer raw, java.nio.ByteBuffer encoded) {
    byte[] raw3 = new byte[3];
    byte[] enc4 = new byte[4];

    while (raw.hasRemaining()) {
      int rem = Math.min(3, raw.remaining());
      raw.get(raw3, 0, rem);
      Base64.encode3to4(enc4, raw3, rem, Base64.NO_OPTIONS);
      encoded.put(enc4);
    }
  }

  /**
   * Performs Base64 encoding on the <code>raw</code> ByteBuffer, writing it to the
   * <code>encoded</code> CharBuffer.
   *
   * This is an experimental feature. Currently it does not pass along any options
   * (such as {@link #DO_BREAK_LINES} or {@link #GZIP}.
   *
   * @param raw input buffer
   * @param encoded output buffer
   * @since 2.3
   */
  public static void encode(java.nio.ByteBuffer raw, java.nio.CharBuffer encoded) {
    byte[] raw3 = new byte[3];
    byte[] enc4 = new byte[4];

    while (raw.hasRemaining()) {
      int rem = Math.min(3, raw.remaining());
      raw.get(raw3, 0, rem);
      Base64.encode3to4(enc4, raw3, rem, Base64.NO_OPTIONS);
      for (int i = 0; i < 4; i++) {
        encoded.put((char)(enc4[i] & 0xFF));
      }
    }
  }

  /**
   * Serializes an object and returns the Base64-encoded version of that serialized object.
   *
   * <p>As of v 2.3, if the object cannot be serialized or there is another error,
   * the method will throw an IOException. <b>This is new to v2.3!</b>.
   *
   * <p>In earlier versions, it just returned a <code>null</code> value, but in retrospect that's a
   * pretty poor way to handle it.
   *
   * <p>The object is not GZip-compressed before being encoded.
   *
   * @param serializableObject The object to encode
   * @return The Base64-encoded object
   *
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if serializedObject is <code>null</code>
   *
   * @since 1.4
   */
  public static String encodeObject(Serializable serializableObject) throws IOException {
    return encodeObject(serializableObject, NO_OPTIONS);
  }

  /**
   * Serializes an object and returns the Base64-encoded version of that serialized object.
   *
   * <p>As of v 2.3, if the object cannot be serialized or there is another error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   *
   * <p>In earlier versions, it just returned a null value, but in retrospect that's a pretty poor way to handle it.
   *
   * <p>The object is not GZip-compressed before being encoded.
   * <p>
   * Example options:<pre>
   *   GZIP: gzip-compresses object before encoding it.
   *   DO_BREAK_LINES: break lines at 76 characters
   * </pre>
   * <p>
   * Example: <code>encodeObject( myObj, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeObject( myObj, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
   *
   * @param o The object to encode
   * @param options Specified options
   *
   * @return The Base64-encoded object
   *
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   *
   * @throws java.io.IOException if there is an error
   * @since 2.0
   */
  public static String encodeObject(Serializable o, int options) throws IOException {
    if (o == null) throw new NullPointerException("Cannot serialize a null object.");

    // Streams
    java.io.ByteArrayOutputStream  baos  = null;
    java.io.OutputStream           b64os = null;
    java.util.zip.GZIPOutputStream gzos  = null;
    java.io.ObjectOutputStream     oos   = null;

    try {
      // ObjectOutputStream -> (GZIP) -> Base64 -> ByteArrayOutputStream
      baos  = new java.io.ByteArrayOutputStream();
      b64os = new Base64.OutputStream(baos, ENCODE | options);
      if ((options & GZIP) != 0) {
        // Gzip
        gzos = new java.util.zip.GZIPOutputStream(b64os);
        oos = new java.io.ObjectOutputStream(gzos);
      } else {
        // Not gzipped
        oos = new java.io.ObjectOutputStream(b64os);
      }
      oos.writeObject(o);

    } catch (IOException ex) {
      // Catch it and then throw it immediately so that the finally{} block is called for cleanup.
      throw ex;

    } finally {
      closeQuietly(oos);
      closeQuietly(gzos);
      closeQuietly(b64os);
      closeQuietly(baos);
    }

    // Return value according to relevant encoding.
    try {
      return new String(baos.toByteArray(), PREFERRED_ENCODING);
    } catch (java.io.UnsupportedEncodingException uue){
      // Fall back to some Java default
      return new String(baos.toByteArray());
    }
  }

  /**
   * Encodes a byte array into Base64 notation.
   *
   * Does not GZip-compress data.
   *
   * @param source The data to convert
   * @return The data in Base64-encoded form
   *
   * @throws NullPointerException if source array is <code>null</code>
   * @since 1.4
   */
  public static String encodeBytes(byte[] source) {
    // Since we're not going to have the GZIP encoding turned on,
    // we're not going to have an IOException thrown, so
    // we should not force the user to have to catch it.
    String encoded = null;
    try {
      encoded = encodeBytes(source, 0, source.length, NO_OPTIONS);
    } catch (IOException ex) {
      assert false : ex.getMessage();
    }
    assert encoded != null;
    return encoded;
  }

  /**
   * Encodes a byte array into Base64 notation.
   *
   * <p>
   * Example options:<pre>
   *   GZIP: gzip-compresses object before encoding it.
   *   DO_BREAK_LINES: break lines at 76 characters
   *     <i>Note: Technically, this makes your encoding non-compliant.</i>
   * </pre>
   *
   * <p>Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   *
   * <p>Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
   *
   * <p>As of v 2.3, if there is an error with the GZIP stream,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned a null value, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   *
   * @param source The data to convert
   * @param options Specified options
   * @return The Base64-encoded data as a String
   *
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if source array is <code>null</code>
   *
   * @since 2.0
   */
  public static String encodeBytes(byte[] source, int options) throws IOException {
    return encodeBytes(source, 0, source.length, options);
  }

  /**
   * Encodes a byte array into Base64 notation.
   * Does not GZip-compress data.
   *
   * <p>As of v 2.3, if there is an error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned a null value, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param source The data to convert
   * @param off Offset in array where conversion should begin
   * @param len Length of data to convert
   * @return The Base64-encoded data as a String
   * @throws NullPointerException if source array is null
   * @throws IllegalArgumentException if source array, offset, or length are invalid
   * @since 1.4
   */
  public static String encodeBytes(byte[] source, int off, int len) {
    // Since we're not going to have the GZIP encoding turned on,
    // we're not going to have an IOException thrown, so
    // we should not force the user to have to catch it.
    String encoded = null;
    try {
      encoded = encodeBytes(source, off, len, NO_OPTIONS);
    } catch (IOException ex) {
      assert false : ex.getMessage();
    }
    assert encoded != null;
    return encoded;
  }

  /**
   * Encodes a byte array into Base64 notation.
   * <p>
   * Example options:<pre>
   *   GZIP: gzip-compresses object before encoding it.
   *   DO_BREAK_LINES: break lines at 76 characters
   *     <i>Note: Technically, this makes your encoding non-compliant.</i>
   * </pre>
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP )</code> or
   * <p>
   * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DO_BREAK_LINES )</code>
   *
   * <p>As of v 2.3, if there is an error with the GZIP stream,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned a null value, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param source The data to convert
   * @param off Offset in array where conversion should begin
   * @param len Length of data to convert
   * @param options Specified options
   * @return The Base64-encoded data as a String
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   *
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if source array is <code>null</code>
   * @throws IllegalArgumentException if source array, offset, or length are invalid
   *
   * @since 2.0
   */
  public static String encodeBytes(byte[] source, int off, int len, int options) throws IOException {
    byte[] encoded = encodeBytesToBytes(source, off, len, options);
    // Return value according to relevant encoding.
    try {
      return new String(encoded, PREFERRED_ENCODING);
    } catch (UnsupportedEncodingException ex) {
      return new String(encoded);
    }
  }

  /**
   * Similar to {@link #encodeBytes(byte[])} but returns a byte array instead of instantiating a String.
   *
   * <p>This is more efficient if you're working with I/O streams and have large data sets to encode.
   *
   * @param source The data to convert
   * @return The Base64-encoded data as a byte[] (of ASCII characters)
   *
   * @throws NullPointerException if source array is <code>null</code>
   * @since 2.3.1
   */
  public static byte[] encodeBytesToBytes(byte[] source) {
    byte[] encoded = null;
    try {
      encoded = encodeBytesToBytes(source, 0, source.length, Base64.NO_OPTIONS);
    } catch (IOException ex) {
      assert false : "IOExceptions only come from GZipping, which is turned off: " + ex.getMessage();
    }
    return encoded;
  }

  /**
   * Similar to {@link #encodeBytes(byte[], int, int, int)} but returns a byte array instead of instantiating a String.
   *
   * This is more efficient if you're working with I/O streams and have large data sets to encode.
   *
   * @see Base64#GZIP
   * @see Base64#DO_BREAK_LINES
   *
   * @param source The data to convert
   * @param off Offset in array where conversion should begin
   * @param len Length of data to convert
   * @param options Specified options
   *
   * @return The Base64-encoded data as a String
   *
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if source array is <code>null</code>
   * @throws IllegalArgumentException if source array, offset, or length are invalid
   * @since 2.3.1
   */
  public static byte[] encodeBytesToBytes(byte[] source, int off, int len, int options) throws IOException {
    if (source == null) throw new NullPointerException("Cannot serialize a null array.");
    if (off < 0) throw new IllegalArgumentException("Cannot have negative offset: " + off);
    if (len < 0) throw new IllegalArgumentException("Cannot have length offset: " + len);
    if (off + len > source.length) throw new IllegalArgumentException(String.format(
      "Cannot have offset of %d and length of %d with array of length %d", off, len, source.length));

    // Compress?
    if ((options & GZIP) != 0) {
      java.io.ByteArrayOutputStream baos = null;
      java.util.zip.GZIPOutputStream gzos = null;
      Base64.OutputStream b64os = null;

      try {
        // GZip -> Base64 -> ByteArray
        baos = new java.io.ByteArrayOutputStream();
        b64os = new Base64.OutputStream(baos, ENCODE | options);
        gzos = new java.util.zip.GZIPOutputStream(b64os);

        gzos.write(source, off, len);
        gzos.close();
      } catch (IOException ex) {
        throw ex;
      } finally {
        closeQuietly(gzos);
        closeQuietly(b64os);
        closeQuietly(baos);
      }

      return baos.toByteArray();
    }

    // Else, don't compress. Better not to use streams at all then.
    else {
      boolean breakLines = (options & DO_BREAK_LINES) != 0;

      // int len43 = len * 4 / 3;
      // byte[] outBuff = new byte[ ( len43 ) // Main 4:3
      // + ( (len % 3) > 0 ? 4 : 0 ) // Account for padding
      // + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines
      // Try to determine more precisely how big the array needs to be.
      // If we get it right, we don't have to do an array copy, and
      // we save a bunch of memory.
      int encLen = (len / 3) * 4 + (len % 3 > 0 ? 4 : 0); // Bytes needed for actual encoding
      if (breakLines) {
        encLen += encLen / MAX_LINE_LENGTH; // Plus extra newline characters
      }
      byte[] outBuff = new byte[ encLen ];


      int d = 0;
      int e = 0;
      int len2 = len - 2;
      int lineLength = 0;
      for ( ; d < len2; d += 3, e += 4) {
        encode3to4(source, d+off, 3, outBuff, e, options);
        lineLength += 4;
        if (breakLines && lineLength >= MAX_LINE_LENGTH) {
          outBuff[e+4] = NEW_LINE;
          e++;
          lineLength = 0;
        }
      }

      if (d < len) {
        encode3to4(source, d+off, len - d, outBuff, e, options);
        e += 4;
      }

      // Only resize array if we didn't guess it right.
      if (e <= outBuff.length - 1) {
        // If breaking lines and the last byte falls right at the line length (76 bytes per line),
        // there will be one extra byte, and the array will need to be resized.
        // Not too bad of an estimate on array size, I'd say.
        byte[] finalOut = new byte[e];
        System.arraycopy(outBuff, 0, finalOut, 0, e);
        return finalOut;
      } else // No need to resize array.
      return outBuff;
    }
  }


  // Decoding methods
  // ----------------------------------------------------------------------------------------------

  /**
   * Decodes four bytes from array <var>source</var>
   * and writes the resulting bytes (up to three of them)
   * to <var>destination</var>.
   * The source and destination arrays can be manipulated
   * anywhere along their length by specifying
   * <var>srcOffset</var> and <var>destOffset</var>.
   * This method does not check to make sure your arrays
   * are large enough to accomodate <var>srcOffset</var> + 4 for
   * the <var>source</var> array or <var>destOffset</var> + 3 for
   * the <var>destination</var> array.
   * This method returns the actual number of bytes that
   * were converted from the Base64 encoding.
   * <p>This is the lowest level of the decoding methods with
   * all possible parameters.</p>
   *
   *
   * @param source the array to convert
   * @param srcOffset the index where conversion begins
   * @param destination the array to hold the conversion
   * @param destOffset the index where output will be put
   * @param options alphabet type is pulled from this (standard, url-safe, ordered)\
   *
   * @return the number of decoded bytes converted
   *
   * @throws NullPointerException if source or destination arrays are null
   * @throws IllegalArgumentException if srcOffset or destOffset are invalid
   *         or there is not enough room in the array.
   * @since 1.3
   */
  private static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset, int options) {

    // Lots of error checking and exception throwing
    if (source == null) throw new NullPointerException("Source array was null.");
    if (destination == null) throw new NullPointerException("Destination array was null.");
    if (srcOffset < 0 || srcOffset + 3 >= source.length) throw new IllegalArgumentException(String.format(
        "Source array with length %d cannot have offset of %d and still process four bytes.", source.length, srcOffset));
    if (destOffset < 0 || destOffset + 2 >= destination.length) throw new IllegalArgumentException(String.format(
        "Destination array with length %d cannot have offset of %d and still store three bytes.", destination.length,
        destOffset));

    byte[] DECODABET = getDecodabet( options );

    // Example: Dk==
    if (source[ srcOffset + 2] == EQUALS_SIGN) {
      int outBuff =   ((DECODABET[ source[ srcOffset    ] ] & 0xFF) << 18)
                    | ((DECODABET[ source[ srcOffset + 1] ] & 0xFF) << 12);
      destination[ destOffset ] = (byte)(outBuff >>> 16);
      return 1;
    }

    // Example: DkL=
    else if (source[ srcOffset + 3 ] == EQUALS_SIGN) {
        int outBuff = ((DECODABET[ source[ srcOffset     ] ] & 0xFF) << 18)
                    | ((DECODABET[ source[ srcOffset + 1 ] ] & 0xFF) << 12)
                    | ((DECODABET[ source[ srcOffset + 2 ] ] & 0xFF) <<  6);

        destination[ destOffset     ] = (byte)(outBuff >>> 16);
        destination[ destOffset + 1 ] = (byte)(outBuff >>>  8);
        return 2;
    }

    // Example: DkLE
    else {
      int outBuff = ((DECODABET[source[srcOffset    ]] & 0xFF) << 18)
                  | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12)
                  | ((DECODABET[source[srcOffset + 2]] & 0xFF) <<  6)
                  | ((DECODABET[source[srcOffset + 3]] & 0xFF));

      destination[ destOffset     ] = (byte)(outBuff >> 16);
      destination[ destOffset + 1 ] = (byte)(outBuff >>  8);
      destination[ destOffset + 2 ] = (byte)(outBuff);

      return 3;
    }
  }

  /**
   * Low-level access to decoding ASCII characters in the form of a byte array.
   *
   * <p><strong>Ignores GUNZIP option, if it's set.</strong>
   *
   * <p>This is not generally a recommended method, although it is used internally as part of the
   * decoding process.
   *
   * <p>Special case: if len = 0, an empty array is returned. Still, if you need more speed and
   * reduced memory footprint (and aren't gzipping), consider this method.
   *
   * @param source The Base64 encoded data
   * @return decoded data
   * @since 2.3.1
   */
  public static byte[] decode(byte[] source) throws IOException {
    byte[] decoded = null;
    decoded = decode(source, 0, source.length, Base64.NO_OPTIONS);
    return decoded;
  }

  /**
   * Low-level access to decoding ASCII characters in
   * the form of a byte array. <strong>Ignores GUNZIP option, if
   * it's set.</strong> This is not generally a recommended method,
   * although it is used internally as part of the decoding process.
   * Special case: if len = 0, an empty array is returned. Still,
   * if you need more speed and reduced memory footprint (and aren't
   * gzipping), consider this method.
   *
   * @param source The Base64 encoded data
   * @param off    The offset of where to begin decoding
   * @param len    The length of characters to decode
   * @param options Can specify options such as alphabet type to use
   * @return decoded data
   * @throws java.io.IOException If bogus characters exist in source data
   * @since 1.3
   */
  public static byte[] decode(byte[] source, int off, int len, int options) throws IOException {

    // Lots of error checking and exception throwing
    if (source == null) throw new NullPointerException("Cannot decode null source array.");
    if (off < 0 || off + len > source.length) throw new IllegalArgumentException(String.format(
      "Source array with length %d cannot have offset of %d and process %d bytes.", source.length, off, len));

    if (len == 0) return new byte[0];
    else if (len < 4) throw new IllegalArgumentException(
      "Base64-encoded string must have at least four characters, but length specified was " + len);

    byte[] decodabet = getDecodabet(options);

    int len34 = len * 3 / 4; // Estimate on array size
    byte[] outBuff = new byte[len34]; // Upper limit on size of output
    int outBuffPosn = 0; // Keep track of where we're writing

    byte[] b4 = new byte[4]; // Four byte buffer from source, eliminating white space
    int b4Posn = 0; // Keep track of four byte input buffer
    int i = 0; // Source array counter
    byte sbiDecode = 0; // Special value from DECODABET

    for (i = off; i < off + len; i++) { // Loop through source

      sbiDecode = decodabet[source[i] & 0xFF];

      // White space, Equals sign, or legit Base64 character
      // Note the values such as -5 and -9 in the
      // DECODABETs at the top of the file.
      if (sbiDecode >= WHITE_SPACE_ENC) {
        if (sbiDecode >= EQUALS_SIGN_ENC) {
          b4[b4Posn++] = source[i]; // Save non-whitespace
          if (b4Posn > 3) { // Time to decode?
            outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, options);
            b4Posn = 0;

            // If that was the equals sign, break out of 'for' loop
            if (source[i] == EQUALS_SIGN) {
              break;
            }
          }
        }

      } else // There's a bad input character in the Base64 stream.
      throw new IOException(String.format("Bad Base64 input character decimal %d in array position %d",
          (source[i]) & 0xFF, i));
    }

    byte[] out = new byte[ outBuffPosn ];
    System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
    return out;
  }

  /**
   * Decodes data from Base64 notation, automatically
   * detecting gzip-compressed data and decompressing it.
   *
   * @param s the string to decode
   * @return the decoded data
   *
   * @throws java.io.IOException If there is a problem
   * @since 1.4
   */
  public static byte[] decode(String s) throws IOException {
    return decode(s, NO_OPTIONS);
  }

  /**
   * Decodes data from Base64 notation, automatically
   * detecting gzip-compressed data and decompressing it.
   *
   * @param s the string to decode
   * @param options encode options such as URL_SAFE
   * @return the decoded data
   * @throws java.io.IOException if there is an error
   * @throws NullPointerException if <tt>s</tt> is null
   * @since 1.4
   */
  public static byte[] decode(String s, int options) throws IOException {
    if (s == null) throw new NullPointerException("Input string was null.");

    byte[] bytes;
    try {
      bytes = s.getBytes(PREFERRED_ENCODING);
    } catch (UnsupportedEncodingException ex) {
      bytes = s.getBytes();
    }

    // Decode
    bytes = decode(bytes, 0, bytes.length, options);

    // Check to see if it's gzip-compressed GZIP Magic Two-Byte Number: 0x8b1f (35615)
    boolean dontGunzip = (options & DONT_GUNZIP) != 0;
    if ((bytes != null) && (bytes.length >= 4) && (!dontGunzip)) {

      int head = (bytes[0] & 0xff) | ((bytes[1] << 8) & 0xff00);
      if (java.util.zip.GZIPInputStream.GZIP_MAGIC == head) {
        java.io.ByteArrayInputStream  bais = null;
        java.util.zip.GZIPInputStream gzis = null;
        java.io.ByteArrayOutputStream baos = null;
        byte[] buffer = new byte[2048];
        int    length = 0;

        try {
          baos = new java.io.ByteArrayOutputStream();
          bais = new java.io.ByteArrayInputStream(bytes);
          gzis = new java.util.zip.GZIPInputStream(bais);

          while ((length = gzis.read(buffer)) >= 0) {
            baos.write(buffer, 0, length);
          }

          // No error? Get new bytes.
          bytes = baos.toByteArray();

        } catch (IOException ex) {
          ex.printStackTrace();
          // Just return originally-decoded bytes
        } finally {
          closeQuietly(baos);
          closeQuietly(gzis);
          closeQuietly(bais);
        }

      }
    }

    return bytes;
  }

  /**
   * Attempts to decode Base64 data and deserialize a Java
   * Object within. Returns <tt>null</tt> if there was an error.
   *
   * @param encodedObject The Base64 data to decode
   * @return The decoded and deserialized object
   * @throws NullPointerException if encodedObject is null
   * @throws java.io.IOException if there is a general error
   * @throws ClassNotFoundException if the decoded object is of a
   *         class that cannot be found by the JVM
   * @since 1.5
   */
  public static Object decodeToObject(String encodedObject) throws IOException, java.lang.ClassNotFoundException {
    return decodeToObject(encodedObject, NO_OPTIONS, null);
  }

  /**
   * Attempts to decode Base64 data and deserialize a Java
   * Object within. Returns <tt>null</tt> if there was an error.
   * If <tt>loader</tt> is not null, it will be the class loader
   * used when deserializing.
   *
   * @param encodedObject The Base64 data to decode
   * @param options Various parameters related to decoding
   * @param loader Optional class loader to use in deserializing classes.
   * @return The decoded and deserialized object
   * @throws NullPointerException if encodedObject is null
   * @throws java.io.IOException if there is a general error
   * @throws ClassNotFoundException if the decoded object is of a
   *         class that cannot be found by the JVM
   * @since 2.3.4
   */
  public static Object decodeToObject(String encodedObject, int options, final ClassLoader loader)
    throws IOException, java.lang.ClassNotFoundException {

    // Decode and gunzip if necessary
    byte[] objBytes = decode(encodedObject, options);

    java.io.ByteArrayInputStream  bais = null;
    java.io.ObjectInputStream     ois  = null;
    Object obj = null;

    try {
      bais = new java.io.ByteArrayInputStream(objBytes);

      if (loader == null) {

        // If no custom class loader is provided, use Java's builtin OIS.
        ois  = new java.io.ObjectInputStream(bais);

      } else {

        // Else make a customized object input stream that uses the provided class loader.
        ois = new java.io.ObjectInputStream(bais) {
          @Override
          public Class<?> resolveClass(java.io.ObjectStreamClass streamClass)
          throws IOException, ClassNotFoundException {
            Class<?> c = Class.forName(streamClass.getName(), false, loader);
            if (c == null) return super.resolveClass(streamClass);
            else return c;   // Class loader knows of this class.
          }
        };
      }

      obj = ois.readObject();
    } catch (IOException ex) {
      throw ex;
    } catch (java.lang.ClassNotFoundException ex) {
      throw ex;
    } finally {
      closeQuietly(bais);
      closeQuietly(ois);
    }

    return obj;
  }

  /**
   * Convenience method for encoding data to a file.
   *
   * <p>As of v 2.3, if there is a error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned false, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param dataToEncode byte array of data to encode in base64 form
   * @param filename Filename for saving encoded data
   * @throws IOException if there is an error
   * @throws NullPointerException if dataToEncode is null
   * @since 2.1
   */
  public static void encodeToFile(byte[] dataToEncode, String filename) throws IOException {
    if (dataToEncode == null) throw new NullPointerException("Data to encode was null.");
    Base64.OutputStream bos = null;
    try {
      bos = new Base64.OutputStream(new java.io.FileOutputStream(filename), Base64.ENCODE);
      bos.write(dataToEncode);
    } catch (IOException ex) {
      throw ex;
    } finally {
      closeQuietly(bos);
    }
  }

  /**
   * Convenience method for decoding data to a file.
   *
   * <p>As of v 2.3, if there is a error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned false, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param dataToDecode Base64-encoded data as a string
   * @param filename Filename for saving decoded data
   * @throws java.io.IOException if there is an error
   * @since 2.1
   */
  public static void decodeToFile(String dataToDecode, String filename) throws IOException {
    Base64.OutputStream bos = null;
    try {
      bos = new Base64.OutputStream(new java.io.FileOutputStream(filename), Base64.DECODE);
      bos.write(dataToDecode.getBytes(PREFERRED_ENCODING));
    } catch (IOException ex) {
      throw ex;
    } finally {
      closeQuietly(bos);
    }
  }

  /**
   * Convenience method for reading a base64-encoded
   * file and decoding it.
   *
   * <p>As of v 2.3, if there is a error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned false, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param filename Filename for reading encoded data
   * @return decoded byte array
   * @throws java.io.IOException if there is an error
   * @since 2.1
   */
  public static byte[] decodeFromFile(String filename) throws IOException {

    byte[] decodedData = null;
    Base64.InputStream bis = null;
    try {
      // Set up some useful variables
      java.io.File file = new java.io.File(filename);
      byte[] buffer = null;
      int length   = 0;
      int numBytes = 0;

      // Check for size of file
      if (file.length() > Integer.MAX_VALUE) throw new IOException("File is too big for this convenience method (" + file.length() + " bytes).");
      buffer = new byte[ (int)file.length() ];

      // Open a stream
      bis = new Base64.InputStream(
                new java.io.BufferedInputStream(
                new java.io.FileInputStream(file)), Base64.DECODE);

      // Read until done
      while ((numBytes = bis.read(buffer, length, 4096)) >= 0) {
        length += numBytes;
      }

      // Save in a variable to return
      decodedData = new byte[ length ];
      System.arraycopy(buffer, 0, decodedData, 0, length);

    } catch (IOException ex) {
      throw ex;
    } finally {
      closeQuietly(bis);
    }

    return decodedData;
  }

  /**
   * Convenience method for reading a binary file
   * and base64-encoding it.
   *
   * <p>As of v 2.3, if there is a error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned false, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param filename Filename for reading binary data
   * @return base64-encoded string
   *
   * @throws java.io.IOException if there is an error
   * @since 2.1
   */
  public static String encodeFromFile(String filename) throws IOException {
    return encodeFromFile(new File(filename));
  }

  /**
   * Convenience method for reading a binary file
   * and base64-encoding it.
   *
   * <p>As of v 2.3, if there is a error,
   * the method will throw an java.io.IOException. <b>This is new to v2.3!</b>
   * In earlier versions, it just returned false, but
   * in retrospect that's a pretty poor way to handle it.</p>
   *
   * @param file the file for reading binary data
   * @return base64-encoded string
   *
   * @throws java.io.IOException if there is an error
   * @since 2.1
   */
  public static String encodeFromFile(File file) throws IOException {
    String encodedData = null;
    Base64.InputStream bis = null;
    try {
      // Need max() for math on small files (v2.2.1); Need +1 for a few corner cases (v2.3.5)
      byte[] buffer = new byte[Math.max((int)(file.length() * 1.4 + 1), 40)];
      int length   = 0;
      int numBytes = 0;

      // Open a stream
      bis = new Base64.InputStream(
                new java.io.BufferedInputStream(
                new java.io.FileInputStream(file)), Base64.ENCODE);

      // Read until done
      while ((numBytes = bis.read(buffer, length, 4096)) >= 0) {
        length += numBytes;
      }

      // Save in a variable to return
      encodedData = new String(buffer, 0, length, Base64.PREFERRED_ENCODING);

    } catch (IOException ex) {
      throw ex;
    } finally {
      closeQuietly(bis);
    }

    return encodedData;
  }

  /**
   * Reads <tt>infile</tt> and encodes it to <tt>outfile</tt>.
   *
   * @param infile Input file
   * @param outfile Output file
   * @throws java.io.IOException if there is an error
   * @since 2.2
   */
  public static void encodeFileToFile(String infile, String outfile) throws IOException {
    String encoded = Base64.encodeFromFile(infile);
    java.io.OutputStream out = null;
    try {
      out = new java.io.BufferedOutputStream(new java.io.FileOutputStream(outfile));
      out.write(encoded.getBytes("US-ASCII")); // Strict, 7-bit output.
    } catch (IOException ex) {
      throw ex;
    } finally {
      closeQuietly(out);
    }
  }

  /**
   * Reads <tt>infile</tt> and decodes it to <tt>outfile</tt>.
   *
   * @param infile Input file
   * @param outfile Output file
   *
   * @throws java.io.IOException if there is an error
   * @since 2.2
   */
  public static void decodeFileToFile(String infile, String outfile) throws IOException {
    byte[] decoded = Base64.decodeFromFile(infile);
    java.io.OutputStream out = null;
    try {
      out = new java.io.BufferedOutputStream(new java.io.FileOutputStream(outfile));
      out.write(decoded);
    } catch (IOException ex) {
      throw ex;
    } finally {
      closeQuietly(out);
    }
  }

  /**
   * Quietly closes the input stream.
   *
   * @param is the stream to close.
   */
  private static void closeQuietly(java.io.InputStream is) {
    try {
      if (is != null) {
        is.close();
      }
    } catch (IOException ex) {
      // Do nothing
    }
  }

  /**
   * Quietly closes the output stream.
   *
   * @param os the stream to close.
   */
  private static void closeQuietly(java.io.OutputStream os) {
    try {
      if (os != null) {
        os.close();
      }
    } catch (IOException ex) {
      // Do nothing
    }
  }

  // Inner class input stream
  // ==============================================================================================

  /**
   * A {@link Base64.InputStream} will read data from another
   * <tt>java.io.InputStream</tt>, given in the constructor,
   * and encode/decode to/from Base64 notation on the fly.
   *
   * @see Base64
   * @since 1.3
   */
  public static final class InputStream extends java.io.FilterInputStream {

    /** Encoding or decoding. */
    private boolean encode;
    /** Current position in the buffer. */
    private int     position;
    /** Small buffer holding converted data. */
    private byte[]  buffer;
    /** Length of buffer (3 or 4) */
    private int     bufferLength;
    /** Number of meaningful bytes in the buffer */
    private int     numSigBytes;
    private int     lineLength;
    /** Break lines at less than 80 characters */
    private boolean breakLines;
    /** Record options used to create the stream. */
    private int     options;
    /** Local copies to avoid extra method calls */
    private byte[]  decodabet;

    /**
     * Constructs a {@link Base64.InputStream} in DECODE mode.
     *
     * @param in the <tt>java.io.InputStream</tt> from which to read data.
     * @since 1.3
     */
    public InputStream(java.io.InputStream in) {
      this(in, DECODE);
    }

    /**
     * Constructs a {@link Base64.InputStream} in
     * either ENCODE or DECODE mode.
     * <p>
     * Valid options:<pre>
     *   ENCODE or DECODE: Encode or Decode as data is read.
     *   DO_BREAK_LINES: break lines at 76 characters
     *     (only meaningful when encoding)</i>
     * </pre>
     * <p>
     * Example: <code>new Base64.InputStream( in, Base64.DECODE )</code>
     *
     *
     * @param in the <tt>java.io.InputStream</tt> from which to read data.
     * @param options Specified options
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DO_BREAK_LINES
     * @since 2.0
     */
    public InputStream(java.io.InputStream in, int options) {
      super(in);
      this.options      = options; // Record for later
      this.breakLines   = (options & DO_BREAK_LINES) > 0;
      this.encode       = (options & ENCODE) > 0;
      this.bufferLength = this.encode ? 4 : 3;
      this.buffer       = new byte[ this.bufferLength ];
      this.position     = -1;
      this.lineLength   = 0;
      this.decodabet    = getDecodabet(options);
    }

    /**
     * Reads enough of the input stream to convert to/from Base64 and returns the next byte.
     *
     * {@inheritDoc}
     *
     * @return next byte
     * @since 1.3
     */
    @Override
    public int read() throws IOException  {

      // Do we need to get data?
      if (this.position < 0) {
        if (this.encode) {
          byte[] b3 = new byte[3];
          int numBinaryBytes = 0;
          for (int i = 0; i < 3; i++) {
            int b = this.in.read();

            // If end of stream, b is -1.
            if (b >= 0) {
              b3[i] = (byte)b;
              numBinaryBytes++;
            } else {
              break; // out of for loop
            }

          } // end for: each needed input byte

          if (numBinaryBytes > 0) {
            encode3to4(b3, 0, numBinaryBytes, this.buffer, 0, this.options);
            this.position = 0;
            this.numSigBytes = 4;
          } else return -1;  // Must be end of stream
        }

        // Else decoding
        else {
          byte[] b4 = new byte[4];
          int i = 0;
          for (i = 0; i < 4; i++) {
            // Read four "meaningful" bytes:
            int b = 0;
            do { b = this.in.read(); }
            while (b >= 0 && this.decodabet[ b & 0x7f ] <= WHITE_SPACE_ENC);
            if (b < 0) {
              break; // Reads a -1 if end of stream
            }
            b4[i] = (byte)b;
          }   // end for: each needed input byte

          if (i == 4) {
            // if: got four characters
            this.numSigBytes = decode4to3(b4, 0, this.buffer, 0, this.options);
            this.position = 0;
          } else if (i == 0) // if: also padded correctly
          return -1;
          else // Must have broken out from above.
          throw new IOException("Improperly padded Base64 input.");

        }   // end else: decode
      }   // end else: get data

      // Got data?
      if (this.position >= 0) {
        // End of relevant data?
        if (/*!encode &&*/ this.position >= this.numSigBytes) return -1;

        if (this.encode && this.breakLines && this.lineLength >= MAX_LINE_LENGTH) {
          this.lineLength = 0;
          return '\n';
        } else {
          this.lineLength++; // This isn't important when decoding but throwing an extra "if" seems just as wasteful.

          int b = this.buffer[ this.position++ ];

          if (this.position >= this.bufferLength) {
            this.position = -1;
          }
          return b & 0xFF; // This is how you "cast" a byte that's intended to be unsigned.
        }
      } else throw new IOException("Error in Base64 code reading stream.");
    }


    /**
     * Calls {@link #read()} repeatedly until the end of stream is reached or <var>len</var> bytes are read.
     *
     * <p>Returns number of bytes read into array or -1 if end of stream is encountered.
     *
     * {@inheritDoc}
     *
     * @param dest array to hold values
     * @param off offset for array
     * @param len max number of bytes to read into array
     * @return bytes read into array or -1 if end of stream is encountered.
     * @since 1.3
     */
    @Override
    public int read(byte[] dest, int off, int len) throws IOException {
      int i;
      int b;
      for (i = 0; i < len; i++) {
        b = read();
        if (b >= 0) {
          dest[off + i] = (byte) b;
        } else if (i == 0) return -1;
        else {
          break; // Out of 'for' loop
        }
      }
      return i;
    }

  }


  // Inner class output stream
  // ==============================================================================================

  /**
   * A {@link Base64.OutputStream} will write data to another
   * <tt>java.io.OutputStream</tt>, given in the constructor,
   * and encode/decode to/from Base64 notation on the fly.
   *
   * @see Base64
   * @since 1.3
   */
  public static final class OutputStream extends java.io.FilterOutputStream {

    private boolean encode;
    private int     position;
    private byte[]  buffer;
    private int     bufferLength;
    private int     lineLength;
    private boolean breakLines;
    /** Scratch used in a few places */
    private byte[]  b4;
    private boolean suspendEncoding;
    /** Record for later */
    private int     options;
    /** Local copies to avoid extra method calls */
    private byte[]  decodabet;

    /**
     * Constructs a {@link Base64.OutputStream} in ENCODE mode.
     *
     * @param out the <tt>java.io.OutputStream</tt> to which data will be written.
     * @since 1.3
     */
    public OutputStream(java.io.OutputStream out) {
      this(out, ENCODE);
    }

    /**
     * Constructs a {@link Base64.OutputStream} in
     * either ENCODE or DECODE mode.
     * <p>
     * Valid options:<pre>
     *   ENCODE or DECODE: Encode or Decode as data is read.
     *   DO_BREAK_LINES: don't break lines at 76 characters
     *     (only meaningful when encoding)</i>
     * </pre>
     * <p>
     * Example: <code>new Base64.OutputStream( out, Base64.ENCODE )</code>
     *
     * @param out the <tt>java.io.OutputStream</tt> to which data will be written.
     * @param options Specified options.
     * @see Base64#ENCODE
     * @see Base64#DECODE
     * @see Base64#DO_BREAK_LINES
     * @since 1.3
     */
    public OutputStream(java.io.OutputStream out, int options) {
      super(out);
      this.breakLines   = (options & DO_BREAK_LINES) != 0;
      this.encode       = (options & ENCODE) != 0;
      this.bufferLength = this.encode ? 3 : 4;
      this.buffer       = new byte[ this.bufferLength ];
      this.position     = 0;
      this.lineLength   = 0;
      this.suspendEncoding = false;
      this.b4           = new byte[4];
      this.options      = options;
      this.decodabet    = getDecodabet(options);
    }

    /**
     * Writes the byte to the output stream after converting to/from Base64 notation.
     *
     * <p>When encoding, bytes are buffered three at a time before the output stream actually
     * gets a write() call.
     *
     * <p>When decoding, bytes are buffered four at a time.
     *
     * {@inheritDoc}
     *
     * @param theByte the byte to write
     * @since 1.3
     */
    @Override
    public void write(int theByte) throws IOException {
      // Encoding suspended?
      if (this.suspendEncoding) {
        this.out.write(theByte);
        return;
      }

      // Encode?
      if (this.encode) {
        this.buffer[ this.position++ ] = (byte)theByte;
        if (this.position >= this.bufferLength) { // Enough to encode.

          this.out.write(encode3to4(this.b4, this.buffer, this.bufferLength, this.options));

          this.lineLength += 4;
          if (this.breakLines && this.lineLength >= MAX_LINE_LENGTH) {
            this.out.write(NEW_LINE);
            this.lineLength = 0;
          }

          this.position = 0;
        }
      }

      // Else, Decoding
      else {
        // Meaningful Base64 character?
        if (this.decodabet[ theByte & 0x7f ] > WHITE_SPACE_ENC) {
          this.buffer[ this.position++ ] = (byte)theByte;
          if (this.position >= this.bufferLength) {
            int len = Base64.decode4to3(this.buffer, 0, this.b4, 0, this.options);
            this.out.write(this.b4, 0, len);
            this.position = 0;
          }
        } else if (this.decodabet[ theByte & 0x7f ] != WHITE_SPACE_ENC) throw new IOException("Invalid character in Base64 data.");
      }
    }

    /**
     * Calls {@link #write(int)} repeatedly until <var>len</var> bytes are written.
     *
     * {@inheritDoc}
     *
     * @param theBytes array from which to read bytes
     * @param off offset for array
     * @param len max number of bytes to read into array
     * @since 1.3
     */
    @Override
    public void write(byte[] theBytes, int off, int len) throws IOException {
      // Encoding suspended?
      if (this.suspendEncoding) {
        this.out.write(theBytes, off, len);
        return;
      }
      for (int i = 0; i < len; i++) {
          write(theBytes[ off + i ]);
      }
    }

    /**
     * Pads the buffer without closing the stream.
     *
     * @throws java.io.IOException  if there's an error.
     */
    public void flushBase64() throws IOException {
      if (this.position > 0) {
        if (this.encode) {
          this.out.write(encode3to4(this.b4, this.buffer, this.position, this.options));
          this.position = 0;
        } else throw new IOException("Base64 input not properly padded.");
      }

    }

    /**
     * Flushes and closes (I think, in the superclass) the stream.
     *
     * {@inheritDoc}
     *
     * @since 1.3
     */
    @Override
    public void close() throws IOException {
      // 1. Ensure that pending characters are written
      flushBase64();

      // 2. Actually close the stream (Base class both flushes and closes)
      super.close();

      this.buffer = null;
      this.out    = null;
    }

    /**
     * Suspends encoding of the stream.
     *
     * <p>May be helpful if you need to embed a piece of base64-encoded data in a stream.
     *
     * @throws java.io.IOException  if there's an error flushing
     * @since 1.5.1
     */
    public void suspendEncoding() throws IOException  {
      flushBase64();
      this.suspendEncoding = true;
    }

    /**
     * Resumes encoding of the stream.
     *
     * <p>May be helpful if you need to embed a piece of base64-encoded data in a stream.
     *
     * @since 1.5.1
     */
    public void resumeEncoding() {
      this.suspendEncoding = false;
    }

  }


}
